title: Carboxymethylation of ulvan and chitosan and their use as polymeric components of bone cements.
abstract: Ulvan, extracted from the green algae Ulva lactuca, and chitosan, extracted from Loligo forbesis squid-pen, were carboxymethylated, yielding polysaccharides with an average degree of substitution of ∼98% (carboxymethyl ulvan, CMU) and ∼87% (carboxymethyl chitosan, N,O-CMC). The carboxymethylation was confirmed by Fourier transform infrared spectroscopy and quantified by conductimetric titration and 1H nuclear magnetic resonance. The average molecular weight increased with the carboxymethylation (chitosan, Mn 145→296 kDa and Mw 227→416 kDa; ulvan, Mn 139→261 kDa and Mw 368→640 kDa), indicating successful chemical modifications. Mixtures of the modified polysaccharides were tested in the formulation of polyacrylic acid-free glass-ionomer bone cements. Mechanical and in vitro bioactivity tests indicate that the inclusion of CMU in the cement formulation, i.e. 0.50:0.50 N,O-CMC:CMU, enhances its mechanical performance (compressive strength 52.4±8.0 MPa and modulus 2.3±0.3 GPa), generates non-cytotoxic cements and induces the diffusion of Ca and/or P-based moieties from the surface to the bulk of the cements.
authors.affiliation: 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, 4806-909 Taipas, Guimarães, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
authors.forename: A A A
authors.initials: AA
authors.lastname: Barros
authors.forename: A
authors.initials: A
authors.lastname: Alves
authors.forename: C
authors.initials: C
authors.lastname: Nunes
authors.forename: M A
authors.initials: MA
authors.lastname: Coimbra
authors.forename: R A
authors.initials: RA
authors.lastname: Pires
authors.forename: R L
authors.initials: RL
authors.lastname: Reis
mesh_terms: D000107:Acetylation / Q000187:drug effects; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry / Q000494:pharmacology; D001843:Bone Cements / Q000737:chemistry / Q000494:pharmacology*; D002118:Calcium / Q000032:analysis; D016923:Cell Death / Q000187:drug effects; D048271:Chitosan / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D019245:Compressive Strength / Q000187:drug effects; D055119:Elastic Modulus / Q000187:drug effects; D005899:Glass Ionomer Cements / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008422:Materials Testing; D051379:Mice; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D010758:Phosphorus / Q000032:analysis; D011108:Polymers / Q000737:chemistry / Q000494:pharmacology*; D011134:Polysaccharides / Q000737:chemistry / Q000494:pharmacology*; D016062:Porosity; D013052:Spectrometry, X-Ray Emission; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; D001843:Bone Cements; D005899:Glass Ionomer Cements; D011108:Polymers; D011134:Polysaccharides; C514968:carboxymethyl-chitosan; C571831:ulvan; D014867:Water; D010758:Phosphorus; D048271:Chitosan; D002118:Calcium
keywords: Bone cements; Carboxymethylation; Chitosan; Glass-ionomers; Ulvan